I think the vest is really good. I got the lv 200 one.
It can be compounded with HP and it is way easier to temper compared with the dragon vest. Tho the HP is lower is prolly the only con. (Not to mention they are forcing the DX on us...)
The set is very cute too. Tho I had no luck with the pet. Good luck to those who are trying to get it. ^^